This invention relates to a reversible rotary compressor adapted for use in refrigeration systems, and more particularly as applied to heat-pump type air conditioners wherein the operation of the refrigeration system can automatically be switched from cooling operation to heating operation or vice versa, without using a directional control valve which have been employed in conventional heat pump-type air conditioners for changing the direction of flow of a refrigerant passing through a refrigerant circuit.
Conventional compressors for refrigeration systems are generally classified into a reciprocating and a rotary type. The reciprocating type compressor has the disadvantage that the flowing direction of refrigerant cannot be reversed. The rotary type compressors generally have a suction port only on the suction side and a discharge port only on the discharge side with respect to the pressure transition point. With the suction and discharge directions so fixed, practical use of such a compressor as a reversible compressor is not possible.
One form of reversible rotary compressor is disclosed in U.S. Pat. No. 2,342,174 wherein a mechanically operated reversing valve is arranged in the casing. The reversing valve includes an external member that is mechanically engaged by a member mounted on the motor compressor shaft to shift the external valve member when direction of the shaft is reversed. U.S. Pat. Nos. 2,844,945 and 2,976,698 disclose another form of reversible rotary compressor employing various valves and refrigerating and air conditioning system configurations and more particularly for defrosting freezer evaporators of two temperature system. In still another prior art U.S. Pat. No. 3,723,024, a reversible rotary compressor is disclosed wherein a movable suction mechanism is provided that is rotated through a predetermined angle so that the suction opening may be shifted to one side or the other of the pressure transition point.